Prokaryotic & Eukaryotic Cells & Their Organelles — Drills · Grade 10 Science

Chapter: Cells, Membranes & Exchange

What these drills covers

By the end of Prokaryotic & Eukaryotic Cells & Their Organelles you should be able to:

6 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: prokaryote, eukaryote, organelle, nucleus, ribosome, endoplasmic reticulum, Golgi apparatus, mitochondrion.

Problem 1

The clearest structural difference between a prokaryotic and a eukaryotic cell is that prokaryotes lack
  1. a cell membrane
  2. ribosomes
  3. a nucleus enclosed by a membrane
  4. genetic material
Answer and explanation

a nucleus enclosed by a membrane

Prokaryotes have DNA, ribosomes, and a membrane, but no membrane-bound nucleus or other membrane-bound organelles.

Problem 2

A cell packed with mitochondria most likely
  1. stores large amounts of starch
  2. has a high demand for ATP
  3. lacks a nucleus
  4. performs photosynthesis only
Answer and explanation

has a high demand for ATP

Mitochondria carry out the reactions that regenerate most of a cell's ATP, so cells with high energy demands such as muscle contain many.

Problem 3

A typical bacterium is about 2 µm long and a typical animal cell about 20 µm. How many times longer is the animal cell?
Answer and explanation

10

20 / 2 = 10 times longer in one dimension, which corresponds to about 1,000 times the volume.

Problem 4

Which pair of organelles is found in plant cells but not in animal cells?
  1. Mitochondria and ribosomes
  2. Chloroplasts and a large central vacuole
  3. Nucleus and cytoplasm
  4. Cell membrane and endoplasmic reticulum
Answer and explanation

Chloroplasts and a large central vacuole

Chloroplasts and a large central vacuole are characteristic of plant cells; both cell types share the other structures listed.

Problem 5

Mitochondria and chloroplasts contain their own small circular DNA and their own ribosomes, and divide independently of the cell. Explain what hypothesis this supports and why.
Answer and explanation

It supports the endosymbiotic hypothesis: these organelles descend from free-living prokaryotes that were taken into an early eukaryotic cell. Circular DNA, prokaryote-like ribosomes, a double membrane, and independent division are the features expected of a former independent cell and are not expected of a compartment built by the host, which is why the pattern counts as evidence rather than coincidence.

Response criteria

  • State a biologically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 6

Trace the path of a protein destined for secretion, naming the organelles in order and what each contributes.
Answer and explanation

A ribosome on the rough endoplasmic reticulum assembles the protein; the endoplasmic reticulum folds it and encloses it in a vesicle; the Golgi apparatus modifies and sorts it and packages it into another vesicle; that vesicle travels to the cell membrane and fuses with it, releasing the protein outside. Each step adds a specific contribution: synthesis, folding, modification and sorting, then export.

Response criteria

  • State a biologically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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